It is known that near field communication (NFC) devices can be used for wireless communication over short distances typically within a range of 1.5 meters. An example of an NFC system is described in WO 2007/072361 A2. A transmitter and a receiver with an antenna circuit are disclosed, the antenna circuit comprising a coil and either a monopole or dipole connected to the coil. The antenna circuit captures a signal with a wavelength transmitted by a transmitter. The coil captures the signal and generates a current having a frequency corresponding to the wavelength. The coil is dimensioned such that the current is distributed uniformly within the coil at each point in time.
An NFC device can be used as a component in many systems such as, without limitation, a keyless entry system. A portable NFC transponder device has an antenna including a coil or inductor which is placed near to a fixed transponder. The fixed NFC transponder controls the lock and is typically powered by a mains supply. The antennae in the two transponders transmit and receive information between the two devices. Furthermore the power transmitted from the fixed transponder to the portable transponder may also be used to provide all the power supply requirements for the portable device if the overall power consumption of the device can be kept small enough. Alternatively the portable transponder may have a small battery although this is typically less desirable. Because of the need to keep power consumption as low as possible, the voltages and currents are small; this can result in loss of information during transmission if the environment is noisy, which is undesirable as a keyless entry system needs to operate reliably. There is therefore a need to develop an improved NFC communication device that can operate reliably with lower power consumption.